C# Synth Toolkit - Part I

#region License

/* Copyright (c) 2007 Leslie Sanford
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy 
 * of this software and associated documentation files (the "Software"), to 
 * deal in the Software without restriction, including without limitation the 
 * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or 
 * sell copies of the Software, and to permit persons to whom the Software is 
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in 
 * all copies or substantial portions of the Software. 
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN 
 * THE SOFTWARE.
 */

#endregion

#region Contact

/*
 * Leslie Sanford
 * Email: jabberdabber@hotmail.com
 */

#endregion

using System;
using System.Collections.Generic;
using System.Diagnostics;
using Sanford.Multimedia.Synth;

namespace SimpleSynthDemo
{
    /// <summary>
    /// Represents a "naive" oscillator capable of producing basic waveforms.
    /// </summary>
    public class SimpleOscillator : StereoSynthComponent, IProgrammable, IBendable
    {
        #region SimpleOscillator Members

        #region Enumerations

        /// <summary>
        /// Constants representing the SimpleOscillator's parameters.
        /// </summary>
        public enum ParameterId
        {
            Panning,
            WaveformType
        }

        /// <summary>
        /// Constants representing the types of waveforms the 
        /// SimpleOscillator can produce.
        /// </summary>
        public enum WaveformType
        {
            Sawtooth,
            Square,
            Triangle
        }        

        #endregion

        #region Fields

        #region Constants

        /// <summary>
        /// The number of waveforms.
        /// </summary>
        public const int WaveformTypeCount = (int)WaveformType.Triangle + 1;

        #endregion

        // Determines the oscillator's position in the stereo field.
        private float panning = 0.5f;

        // The type of waveform the SimpleOscillator is currently producing.
        private WaveformType waveType = WaveformType.Sawtooth;

        // The note that is currently playing.
        private int currentNote;

        // Phase accumulator.
        private float accumulator = 0;

        // The amount to modulate the pitch based on pitch wheel movement.
        private float pitchBendModulation = 0;

        // Indicates whether the SimpleOscillator is currently playing.
        private bool playing = false;

        // Indicates whether the SimpleOscillator will overwrite the 
        // values in its buffer each time it synthesizes output.
        private bool synthesizeReplaceEnabled = true;

        #endregion

        #region Constructors

        public SimpleOscillator(SampleRate sampleRate, StereoBuffer buffer) : base(sampleRate, buffer)
        {
            Initialize();
        }

        public SimpleOscillator(SampleRate sampleRate, StereoBuffer buffer, string name) : base(sampleRate, buffer, name)
        {
            Initialize();
        }

        private void Initialize()
        {
            currentNote = A440NoteNumber;
        }

        #endregion       
 
        #region Methods
        
        public override void Synthesize(int offset, int count)
        {
            // Get StereoBuffer; we'll write the synthesized output to 
            // this buffer.
            float[,] buffer = GetBuffer();

            Debug.Assert(buffer != null);
            Debug.Assert(buffer.GetLength(1) >= offset + count);

            // Synthesized output.
            float output = 0;

            // Modulate the current pitch with pitch bend modulation value. 
            float modNote = currentNote + NotesPerOctave * pitchBendModulation;           

            // If the current pitch was modulated to a negative value 
            // (out of range).
            if(modNote < 0)
            {
                // Clip modulated pitch.
                modNote = 0;
            }
            // Else the current pitch was modulated to a positive value 
            // that is out of range.
            else if(modNote > NoteCount - 1)
            {
                // Clip modulated pitch.
                modNote = NoteCount - 1;
            }

            // Calculate the phase increment value.
            float increment = PowerOfTwoTable.GetPower((modNote - A440NoteNumber) / NotesPerOctave) * A440Frequency / SamplesPerSecond;

            // The end point in the buffer where we stop synthesizing.
            int endIndex = offset + count;

            for(int i = offset; i < endIndex; i++)
            {
                switch(waveType)
                {
                    case WaveformType.Sawtooth:
                        output = 1 - 2 * accumulator;
                        break;

                    case WaveformType.Square:
                        if(accumulator < 0.5)
                        {
                            output = -1;
                        }
                        else
                        {
                            output = 1;
                        }
                        break;

                    case WaveformType.Triangle:
                        if(accumulator < 0.5)
                        {
                            output = 1 - 4 * accumulator;
                        }
                        else
                        {
                            output = 1 - 4 * (1 - accumulator);
                        }
                        break;

                    default:
                        Debug.Fail("Unhandled waveform type.");
                        break;
                }

                if(synthesizeReplaceEnabled)
                {
                    buffer[0, i] = output * (1 - panning);
                    buffer[1, i] = output * panning;
                }
                else
                {
                    buffer[0, i] += output * (1 - panning);
                    buffer[1, i] += output * panning;
                }

                accumulator += increment;

                if(accumulator >= 1)
                {
                    accumulator -= 1;
                }
            }
        }

        public override void Trigger(int previousNote, int note, float velocity)
        {
            currentNote = note;

            playing = true;
        }

        public override void Release(float velocity)
        {
            playing = false;
        }

        #endregion

        #region Properties

        public override bool SynthesizeReplaceEnabled
        {
            get
            {
                return synthesizeReplaceEnabled;
            }
            set
            {
                synthesizeReplaceEnabled = value;
            }
        }

        public override int Ordinal
        {
            get
            {
                return 1;
            }
        }

        public bool IsPlaying
        {
            get
            {
                return playing;
            }
        }        

        #endregion

        #endregion

        #region IProgrammable Members

        public string GetParameterName(int index)
        {
            #region Require

            if(index < 0 || index >= ParameterCount)
            {
                throw new ArgumentOutOfRangeException("index");
            }

            #endregion

            string result = string.Empty;
            string name = Name;

            if(!string.IsNullOrEmpty(name))
            {
                name = name + " ";
            }

            switch((ParameterId)index)
            {
                case ParameterId.Panning:
                    result = name + "Panning";
                    break;

                case ParameterId.WaveformType:
                    result = name + "Waveform";
                    break;

                default:
                    Debug.Fail("Unhandled parameter.");
                    break;
            }

            return result;
        }

        public string GetParameterLabel(int index)
        {
            #region Require

            if(index < 0 || index >= ParameterCount)
            {
                throw new ArgumentOutOfRangeException("index");
            }

            #endregion

            string result = string.Empty;

            switch((ParameterId)index)
            {
                case ParameterId.Panning:
                    result = "Left/Right";
                    break;

                case ParameterId.WaveformType:
                    result = "Type";
                    break;

                default:
                    Debug.Fail("Unhandled parameter.");
                    break;
            }

            return result;
        }

        public string GetParameterDisplay(int index)
        {
            #region Require

            if(index < 0 || index >= ParameterCount)
            {
                throw new ArgumentOutOfRangeException("index");
            }

            #endregion

            string result = string.Empty;

            switch((ParameterId)index)
            {
                case ParameterId.Panning:
                    {
                        float position = panning * 2 - 1;

                        result = position.ToString("F");
                    }
                    break;

                case ParameterId.WaveformType:
                    result = waveType.ToString();
                    break;

                default:
                    Debug.Fail("Unhandled parameter.");
                    break;
            }

            return result;
        }

        public float GetParameterValue(int index)
        {
            #region Require

            if(index < 0 || index >= ParameterCount)
            {
                throw new ArgumentOutOfRangeException("index");
            }

            #endregion

            float result = 0;

            switch((ParameterId)index)
            {
                case ParameterId.Panning:
                    result = panning;
                    break;

                case ParameterId.WaveformType:
                    result = (float)(int)waveType / (WaveformTypeCount - 1);
                    break;

                default:
                    Debug.Fail("Unhandled parameter.");
                    break;
            }

            return result;
        }

        public void SetParameterValue(int index, float value)
        {
            #region Require

            if(index < 0 || index >= ParameterCount)
            {
                throw new ArgumentOutOfRangeException("index");
            }
            else if(value < 0 || value > 1)
            {
                throw new ArgumentOutOfRangeException("value");
            }

            #endregion

            switch((ParameterId)index)
            {
                case ParameterId.Panning:
                    panning = value;
                    break;

                case ParameterId.WaveformType:
                    waveType = (WaveformType)(int)Math.Round(value * (WaveformTypeCount - 1));
                    break;

                default:
                    Debug.Fail("Unhandled parameter.");
                    break;
            }
        }

        public int ParameterCount
        {
            get
            {
                return (int)ParameterId.WaveformType + 1;
            }
        }

        #endregion

        #region IBendable Members

        public float PitchBendModulation
        {
            get
            {
                return pitchBendModulation;
            }
            set
            {
                pitchBendModulation = value;
            }
        }

        #endregion
    }
}